Use the correct ERT for Emacs 24

Make sure downloaded libraries are removed before testing with
Emacs 24, in particular the *.elc files.
Temporarily disable flow-control test

Because it randomly causes all tests to fail.
Fix and enhancements to slime-trace-dialog contrib.

* contrib/slime-trace-dialog.el
(slime-trace-dialog): Change advertised protocol, doesn't fetch
traces automatically, just specs and progress.
(slime-trace-dialog-fetch-specs): New interactive function.
(slime-trace-dialog-fetch-progress): New interactive function.
(slime-trace-dialog-fetch-status): Fetch local control, specs and
progress.
(slime-trace-dialog--clear-local-tree): Simplified.
(slime-trace-dialog--update-progress): "[refresh]" button degates
to `slime-trace-dialog-fetch-progress'.	 "[clear]" button always
shows if there is something to clear. Simplified.
(slime-trace-dialog--on-new-results): Adapt to new
`slime-trace-dialog--update-progress'
(slime-trace-dialog--mode-map): Bind 'g' to
`slime-trace-dialog-fetch-status'.

* contrib/swank-trace-dialog.lisp (dialog-trace): Don't set RETLIST-OF to a
symbol here, backends are responsible for that.
[Fix #72] Convert HACKING to CONTRIBUTING.md
Merge pull request #81 from bbatsov/contributing

Closes #72: Convert HACKING to CONTRIBUTING.md
Add a top level Makefile

* slime.el: Bump version to 2.0.1

* slime-tests.el (slime-test-ert-for): Use `eval-and-compile' (fixes
  byte-compilation issue).

* Makefile: New file: top level makefile, replaces mkdir.sh and
test.sh. Some elpa targets available, still incomplete.

* .travis.yml (script): Use "make check".

* mkdir.sh: Removed file.

* test.sh: Removed file.
Correctly bump version to 2.3.1, not 2.0.1
Fix: slime-repl-delete-from-input-history saved back the old history entries before the in-memory ones.
Smarter slime-read-from-minibuffer: supports history and keymap.
Always jump to the prompt when navigating the repl history.
Smarter repl history navigation.

- M-r/M-s (or what slime-repl-previous/next-matching-input is bound to) can be used similar to C-s: when pressed multiple times then jumps to the next match with the same regexp

- minibuffer reading of regexp search has its own history, and defaults to the previous input

- pressing M-r while reading the regexp in the minibuffer initiates searching with the previous regexp (like isearch)

- only the sending of the repl input resets the index of navigation history

- drop the feature that the typed-in text at the repl is used as initial history search regexp (the new input method is much more flexible)

- while navigating, display in the minibuffer which repl history index we are at, and what regexp is used for filtering currently

- when reaching the most recent end of the history, then clear the repl input